For more, visit SDSU NewsCenter
Debates around the Green New Deal have largely centered around climate change concerns on land. A new paper from Rebecca Lewison and colleagues explains why policies that integrate terrestrial and ocean approaches are needed to create a robust portfolio of climate adaptation and mitigation measures supporting communities, the environment and the economy. “A Teal Deal combines land and ocean approaches to address climate change, generating economic benefits to communities everywhere,” Lewison said. “The COVID-19 pandemic has shown us that rapid, responsive and coordinated efforts across sectors can stop a crisis. The climate change crisis is ongoing and an integrated policy offers the same opportunity -- to develop a responsive and coordinated multi-sectoral plan for climate resilience.”
For more, visit SDSU NewsCenter
By Dr. Isabel Rojas-Viada
In early Spring, Dr. Megan Jennings and I ventured through the Santa Margarita River gorge, within San Diego State University’s Ecological Reserve, named after the same river. Our task was to deploy temperature data loggers along and across the river, to monitor the gorge’s climates and map climate refugia, part of the project “Connecting Wildlands and Communities”.
Climate refugia are at the core of today’s conservation toolkit as they can protect species’ populations from anthropogenic climate warming, maintaining more stable climates than surrounding sites and having less exposure to extreme weather events like heat waves or droughts. To find these climate stable sites, we will quantify the rate of climate warming across the landscape and assess persistence and behavior of local weather events that alter the effect of regional climate warming. To meet our objectives, we are monitoring microclimates at the Santa Margarita Ecological Reserve to learn what weather events drive climate variability in our region and to adjust coarse scale maps that we are developing with other types of data.
On a misty, sunny morning, we launched our walk along the narrow, sinuous gorge. Our eyes were captured by an ever-changing river, with ponds and short rapids built from rocks of many shapes and colors. Along the river banks, we found riparian ecosystems of various kinds, from wetlands dominated by cattails and giant reeds, to small patches of oaks. Those oaks were gorgeous. By being a more mesic species, they are a sign that microclimates allowed their establishment. I really enjoyed looking at their form and color. They transported me way far south, to the mediterranean rivers in Chile. There, trees of the same color and size, with hard, evergreen, sclerophyllous leaves stand, sharing a similar river and the same sky. We also encountered some wild animals; we saw some of them, we heard others, and we spotted a few of them by the remains of their presence, their scat; enough to know they were close by.
Our walk continued for a long day. Without a trail and little references, we expected some challenges on your way. We crossed the river four times; so staying dry wasn’t easy. We also encountered a patch of prickly pear cactus blocking our way. We had two options, that spiny prickly pear patch or a rocky cliff. Fortunately, we didn’t have to choose one of those options, as Megan neatly cut a path through the patch. I’m not sure what we would have done without Megan’s gloves and knife. You must be prepared for everything when you are out there in the gorge! At the end, and after beating lots and lots of chaparral, we successfully deployed the loggers following our plan.
We will continue our climate monitoring in the Santa Margarita river. Stay tuned about project updates at “Connecting wildlands and communities”. I want to thank the managers of the reserve, Pablo Bryant and James Bourdon, for their support and facilitating our field trips. I acknowledge the contribution of project collaborators: Rebecca Lewison, Dan Cayan, Douglas Alden, Julie Kalansky, Alan and Lorraine Flint.
List of species:
Turkey Vulture, Red-tailed Hawk, American Coot, Acorn Woodpecker, Great Blue heron, Western Scrub-Jay, California Towhee, Yellow-rump Warbler, Common Yellow-throated warbler, Hooded Oriole, American Goldfinch, Wren spp, Mallard, Song Sparrow, American Crow, Pacific-slope Flycatcher, Northern Mockingbird, Anna’s Hummingbird, California Quail.
California tree frog, Bullfrog
Rattlesnake (heard but not seen, so species is unknown!), western fence lizard, whiptail lizard
Bobcat, Coyote, Brush rabbit, ground squirrel, woodrat.
Damselflies, Dragonflies, Swallowtail butterfly, California sister butterfly, Darkling beetle
Coast live oak, Toyon, Willow cottonwood, Salix spp. (Willow), Western Sycamore, Wild grape, California Bee Plant, Indian paintbrush, Fingertips (Dudleya edulis), Chaparral yucca, Poison oak, White sage, Black sage, Laurel sumac, California sagebrush, Sugar bush, Chamise, Ceanothus spp., Gazania, Alder spp., Tree Tobacco, Fan palm, Eucalyptus spp, Morning glory sp., Thistle spp., Miner’s Lettuce, California dodder (Cuscuta californica), Common cryptantha, Phacelia spp., Sticky monkeyflower, Coastal Prickly Pear, Iris spp., Lupinus spp.,
Stinging lupine, Giant reed.
Maintaining landscape connectivity is recognized as critical to protecting viable populations and ecosystems on the landscape. Yet, much of the science around connectivity considers landscape as static, ignoring changes in land use pressure, other stressors and climate change. The Lewison lab is editing a special issue of Land that focuses on landscape connectivity in dynamic systems. The special issue will present cutting edge science on case studies and challenges of dynamic connectivity, best practices and lessons learned for researchers and practitioners, an exploration of the role of stakeholder engagement, social networks and boundary-spanning organizations in successful dynamic connectivity planning, and approaches to support decision-making, prioritization and implementation of dynamic connectivity.
To learn more about the special issue (due out in Summer 2020), click here
At the beginning of February, seven members of the lab had the opportunity to travel to the Western Section of the Wildlife Society conference, held this year in Redding, CA. The week spent in Redding was filled with engaging talks, useful workshops, the chance to connect with wildlife colleagues, and lots of quality time with lab mates. We even managed to find an afternoon to go on a hike in nearby Castle Crags State Park. Kylie, Emma, Madi, and Greta all presented posters on their M.S. thesis research, and did an excellent job representing the exciting research going on in the Conservation Ecology Lab!
A new academic year is upon us and with that comes new members joining the lab! To get to know our new Lewison Labmates a bit better we put together a quick Q&A.
Nima Farchadi, Ph.D. Student
Dr. Isabel Rojas-Viada, Postdoctoral Researcher
Stay tuned to see these awesome scientists in action. Welcome to the Lewison Lab!
Widely spread across the western United States, mule deer are the most hunted large mammal in California and serve as the primary prey source of mountain lions – making them an economically and ecologically important harvested species. Populations of harvested species face pressures from both natural predators and competitors as well direct pressures from human hunters, and mule deer are no exception. Wildlife managers must accordingly keep close tabs on deer population numbers to ensure that harvest intensity is sustainable and deer abundance remains relatively stable. However, over the last 30 years, the California mule deer population has exhibited a steady trend of decline. Due to these sustained reductions in California mule deer populations, interest in improving and implementing routine population abundance assessments has arisen for state wildlife managers and citizen-lead mule deer organizations. Therefore, the California Department of Fish and Wildlife (CDFW) has partnered with scientists to develop and execute state-of-the-science deer abundance estimation techniques across the state and assess their effectiveness in various habitat types and landscapes.
Here in San Diego County, the unique climate and topography provides the foundation for a diverse assemblage of species and ecosystem types. The intersection of these various habitats across the county presents logistical challenges when attempting to locate and count deer. Estimation techniques that are effective in open grasslands, such as helicopter wildlife surveys, may not be practical in the dense and concealing chaparral or oak forests that lie adjacent. Kylie Curtis, a Masters student in the Lewison Lab, is one such scientist that is working with CDFW to help overcome these complications and determine the most accurate abundance and density estimation techniques for mule deer inhabiting various habitat types. She will be focusing her efforts on an area in central San Diego County called San Felipe Valley. San Felipe Valley is made up of a mosaic of state and federally owned lands, and is an ecosystem defined by a unique blend of habitat types including chaparral, desert riparian woodland, grasslands, sage scrub, and oak woodlands. This diversity makes San Felipe Valley an excellent study area to determine the viability of estimation methods in a variety of habitats. Ms. Curtis will be focusing her efforts on assessing a method called capture recapture for its effectiveness estimating abundance of deer in the valley.
Capture recapture, also known as mark recapture, is a commonly used abundance estimation method when it is not feasible to count all of the individuals in a population. Traditionally, a portion of a population is captured, marked so that they can be identified in the future, and then released. Then, at a later time, another portion of the population is captured and researchers determine how many of the newly captured animals have marks. The basic assumption behind this method is that the number of marked animals in the second group should be proportional to the number of marked animals in the total population and using this assumption researchers can estimate the total population size by dividing the number of marked individuals by this proportion.
Usually, capture recapture involves physically marking animals with a visible tag. However, with genetic advances over the last 20 years, it is now feasible and affordable to mark animals by obtaining tissues, hairs, or fecal samples. This noninvasive marking process requires that DNA be extracted from the sample, and then the DNA is genotyped and given an individual identity. Once a unique genotype is obtained, this counts as a mark. When future samples are collected and genotyped it is possible that a genotype from one sample will match a genotype from a previous sample and this counts as a recapture of the same individual.
For deer, one of the most readily available and easily collected sources of DNA is scat. Ms. Curtis spent six weeks this summer in San Felipe Valley collecting deer scat to use to estimate deer population size in the area. Along with field work partners Richard Cousins, a CDFW employee that has served over 40 years with the agency, and Tessa Cardinal, a generous volunteer fresh out of Point Loma Nazarene University with a biology degree and passion for large mammals, Ms. Curtis established 24 transects spaced relatively uniformly across the valley that followed deer trails. In the unforgiving summer heat and rough terrain, these workers walked many kilometers collecting scat and recording information on where each sample was collected. Ms. Curtis then took these samples back to the lab to extract DNA and identify individuals. Over the course of the summer, the team collected over 500 scat samples that will have to be processed and genotyped. This work is ongoing, but genotyping is expected to be completed by spring of next year. Once each sample is given an identity, Ms. Curtis can determine if there are recaptures and use this information for her analysis. This will ultimately produce the estimates and tools CDFW needs to continue monitoring deer populations in Southern California and ensuring the continued success of these populations.
Yesterday, over 200 people participated in San Diego's first Climate Summit at the Scripps Institution of Oceanography. The event, organized by the Climate Science Alliance - South Coast, featured a forthcoming report, "San Diego County Ecosystems: The Ecological Impacts of Climate Change on a Biodiversity Hotspot" that will be part of California's Fourth Climate Change Assessment. The day featured an overview presentation about the report, panel discussions with the authors, and the release of an Executive Summary of the report for managers, planners, and decision makers. The day was rounded out with workshops on communicating about climate science and a sunset reception overlooking the ocean.
Dr. Megan Jennings, lead author of the report, helped organize the event. Read more about it in this SDSU News Center article!
Marisa Trego, a PhD Candidate in the Lewison Lab, is the first author of a manuscript published today in Environmental Science & Technology. This project aimed to assess the presence and endocrine potential impact of a large number of organic compounds on short-beaked common dolphins in the Southern California Bight. The evidence presented here suggests that an elevated load of man-made organic contaminants could be contributing to impaired testosterone production in male short-beaked common dolphins. For more information see the full publication here.
South Texas is home to the last remaining breeding populations of ocelots in the U.S. The U.S. Fish and Wildlife Service estimates that fewer than 100 of these beautiful neotropical wildcats remain at the very southern tip of Texas, inhabiting remnant swaths of densely tangled and highly diverse Tamaulipan thornscrub habitat. These isolated populations are vulnerable to a variety of threats, including road-associated mortality. Since monitoring of south Texas ocelots began in 1983, over 50% of recorded mortalities have been attributed to vehicle collisions. In collaboration with USFWS, M.S. student Greta Schmidt is revisiting ocelot mortality data to revamp a database of known road mortalities by linking these mortality sites with landscape and demographic predictors of risk. At the beginning of January, Greta returned to Laguna Atascosa National Wildlife Refuge, where the Ocelot Monitoring and Recovery Program is based, to pore over 30 years of ocelot mortality records in order to verify older (read: the 80s) reports, which involved a lot of fun time spent with a scanner and mountains of old datasheets! This will be the first part of her multi-faceted project exploring the viability of wildlife crossing structures as a mitigation tool to reduce ocelot road mortality risk and restore connectivity of ocelot populations in south Texas.
Bobcats are small carnivores that are widespread in the United States. Beyond a species of conservation interest in their own right, bobcats can also act as an indicator of functional connectivity. That is because bobcats need to disperse, have relatively large home ranges, utilize urban edge, and are resource selection generalists. If bobcat populations can move across a landscape, then it is possible that maybe other plant and animal species can too. If bobcats cannot move across the landscape, then it tells us that the landscape has barriers and is fragmented.
Julia Smith, a Masters candidate in the Lewison lab, is using bobcat genetics to learn more about landscape connectivity. Julia is building a dataset that uses bobcat genetic data from throughout Southern California, in collaboration with the National Park Service, the United States Geological Survey, Colorado State University, and the University of California, Los Angeles. By running microsatellites, a type of genetic marker, Julia will be able to see if there are any differences in bobcat dispersal through a gradient of urbanization in Coastal Southern California.
The Lewison Lab